A MIMO (multiple-input and multiple-output) antenna design of a partial metal housing for 4G handset applications generally includes the antenna working at low, mid and high frequencies (e.g. tri-band), for example, with a low band being a range of 710-960 MHz, a medium band being in a range of 1710-2100 MHz, and high band being in a range of 2300-2600 MHz. The tri-band design can effectively reduce the number of antennae used in mobile applications. However, MIMO tri-band antenna technology in partial metal housing handsets can be challenging as such tri-band antennas should fit into a partial metal back compact phone with multi-operating frequencies, and good diversity and capacity performance. However, the partial metal back can interfere with the antenna; hence, when the tri-band antennas are put in the partial metal back handset, their performance deteriorates.